1. Field
Specific examples discussed hereinbelow relate to a technique for estimating a connection state between devices in a communication network including a plurality of devices.
2. Description of Related Art
It is very important for a user of a communication network to grasp the configuration (the topology and physical positions of nodes) of a network concerned in order to utilize the network and to cope with occurrence of a fault in the network.
On the other hand, in the case that the user intends to utilize a wide area network service provided by a network carrier, the carrier does not make public the internal structure of the network and hence it is difficult for the user to directly grasp the configuration of the network.
Thus, the user may be able to estimate the internal structure of a wide area network on the basis of a Round Trip Time (hereinafter, referred to as an RTT) taken for communication between devices (hereinafter, referred to as an RTT between devices) constituting a communication network concerned. That is, each RTT between respective ones of a plurality of user bases connected together over a wide area network and the number of branch points in the network, connecting relations thereof and their positions (RTTs between the respective branch points and between each branch point and each user base) are estimated on the basis of the calculated RTTs. Specifically, one branch point for connecting together a small number (for example, three) of user bases is assumed to try to find out any inconsistency in the calculated RTT or the assumption and trial are appropriately repeated to estimate the internal structure of the network. As another embodiment, in some cases, the internal structure of the network is estimated by performing empirical and geographical estimation in combination with the above method (see FIG. 1).